70f16c81eeee15b60e0814b60ed59fa0e0a60e20
[wikirepo] / notes / a_40-ish_dB_tap / index.mdwn
1 I build the 40dB tap from the same QST article as my [powermeter](notes/W7ZOI_Power_Meter).
2
3 [[!img IMG_20190702_201621.jpg size=800x600]]
4
5 To make it useful, I need to measure the coupling and insertion loss, so here
6 goes.  S1 and S2 are the through ports, S3 is the tap.  It's pretty flat over
7 7-433MHz, with a through loss of <1dB and a coupling of 34-35dB.
8
9 Test setup is the FT817 in FM mode and lowest power as the signal source, through a 20dB pad to the source port of the coupler, the [powermeter](notes/W7ZOI_Power_Meter) connected to the measured port, and my better [50R termination](notes/Characterising_a_coupler/) for the remaining port.
10
11 <table border="1" class="dataframe">
12   <thead>
13     <tr style="text-align: right;">
14       <th></th>
15       <th>F [MHz]</th>
16       <th>S1S2 [dBm]</th>
17       <th>S1S3 [dBm]</th>
18       <th>S2S3 [dBm]</th>
19       <th>SRC [dBm]</th>
20       <th>loss S1S2 [dBm]</th>
21       <th>loss S2S3 [dBm]</th>
22     </tr>
23   </thead>
24   <tbody>
25     <tr>
26       <th>0</th>
27       <td>7.15</td>
28       <td>4</td>
29       <td>-30</td>
30       <td>-30</td>
31       <td>4</td>
32       <td>0</td>
33       <td>34</td>
34     </tr>
35     <tr>
36       <th>1</th>
37       <td>10.00</td>
38       <td>4</td>
39       <td>-30</td>
40       <td>-29</td>
41       <td>4</td>
42       <td>0</td>
43       <td>33</td>
44     </tr>
45     <tr>
46       <th>2</th>
47       <td>29.00</td>
48       <td>5</td>
49       <td>-29</td>
50       <td>-28</td>
51       <td>5</td>
52       <td>0</td>
53       <td>33</td>
54     </tr>
55     <tr>
56       <th>3</th>
57       <td>50.50</td>
58       <td>5</td>
59       <td>-28</td>
60       <td>-28</td>
61       <td>5</td>
62       <td>0</td>
63       <td>33</td>
64     </tr>
65     <tr>
66       <th>4</th>
67       <td>145.50</td>
68       <td>4</td>
69       <td>-29</td>
70       <td>-29</td>
71       <td>5</td>
72       <td>1</td>
73       <td>34</td>
74     </tr>
75     <tr>
76       <th>5</th>
77       <td>433.00</td>
78       <td>3</td>
79       <td>-30</td>
80       <td>-31</td>
81       <td>3</td>
82       <td>0</td>
83       <td>34</td>
84     </tr>
85   </tbody>
86 </table>
87
88 [[!tag draft radio FT817]]